Supramolecular strategy to construct quantum dot-based sensors for detection of paraoxon

© 2018 Elsevier B.V. The development of advanced tools for sensing specific materials remains an ongoing challenge. Detailed below is a new quantum dot (QD)-based sensor via supramolecular interactions, demonstrating a novel simplicity of design to obtain sensitive QDs while avoiding their covalent cross-linking. A simple label-free and turn-off method for the detection of paraoxon and its degradation products in aqueous media was proposed by using the fluorescent QD/surfactant/cyclodextrin supramolecular system. This nanocomposite was prepared from 3-mercaptopropionic acid-capped CdTe QDs coated with cetyltrimethylammonium bromide (CTAB) through electrostatic self-assembly. Further nanocomposite modification by β-cyclodextrin (β-CD), thanks to hydrophobic interaction between cetyl tails of surfactants and inner cavity of macrocycle contributed to an increase in emission intensity and stability in aqueous solution. The strong fluorescence of CdTe/CTAB/β-CD nanocomposite can be effectively quenched by the addition of paraoxon due to the host–guest complexation between β-CD cavity and paraoxon degradation product. The functionality of the paraoxon sensor was also tested with blood samples of paraoxon-poisoned rats (1/2 × LD50). These fluorescent nanocomposites were obtained by using the simple supramolecular method to coat QDs with surfactant–cyclodextrin shells. This coating strategy potentially offers common method for the functionalization of QDs and avoids time-consuming synthesis procedures

Economic Belt of the Silk Way: opportunities and prospects for Kazakhstan

«One Belt, One Road» – the proposal put forward by the People's Republic of China (PRC) for joint projects of the «Economic belt of the Silk Way» and the «Silk Road of the XXI century». The proposal was first put forward by the Chairman of the People's Republic of China Xi Jinping during his visits to the countries of Central Asia and to Indonesia in the autumn of 2013. The essence of this Chinese initiative is to find, formulate and promote a new model of international cooperation and development by strengthening existing regional bilateral and multilateral mechanisms and structures of interaction involving China. Based on the continuation and development of the spirit of the ancient Silk Road, «One Belt, One Road» calls for the development of new mechanisms for regional economic partnership, stimulation of economic prosperity of the countries involved, strengthening of cultural exchanges and links in all areas between different civilizations, as well as promoting peace and sustainable development. According to official data of China «One Belt, One Road» covers the greater part of Eurasia, connecting developing countries, including «new economies», and developed countries. The territory of the megaproject contains rich reserves of resources, 63% of the world's population live, and the estimated economic scale is 21 trillion US dollars. Against the backdrop of the slow recovery of the world economy from the cosequences of the global financial and economic crisis, the world community is to find a new model of interaction and create new mechanisms for economic development. During the integration of the Chinese economy into the world economy, China is ready to assume more international responsibilities and commitments in accordance with its capabilities, to make a great contribution to the maintenance of peace and human development. The initiative on joint construction of the "one belt and one road" is aimed at promoting free, orderly movement of economic factors, efficient allocation of resources and deepening market integration, encouraging coordination of economic policies of countries along the «one belt and one road» routes, expanding and deepening regional cooperation, on joint efforts the formation of an open, inclusive and balanced architecture of regional cooperation, within the framework of such an architecture partner all are benefiting and opportunities for sustainable development. The article describes the economic content of the Economic Belt of the Silk Way and also discusses the problems and facts that this global project helps to stimulate the development of the Kazakh-Chinese economic relations. Key words: Economic Belt of the Silk Way, Kazakh-Chinese economic relations, system, project, road, interest

The current state of the world oil market

The main issue of the world economy today is the global rise in oil prices. Oil remains the most important primary energy source in the world for the next 30-40 years. According to experts, by 2030 this figure will reach 116 million barrels per day. However, the share of OPEC countries in the world’s proven oil reserves is 83%. The world is facing the threat of a prolonged oil crisis and should be prepared for the fact that oil prices will be high for a long period. OPEC expects an increase in demand for gasoline and distillates in 2018 by almost 1 million barrels per day. The optimism of the cartel is based on the growing demand for petroleum products in the US and the increase in global car sales. The healthy growth of the world economy, good sales figures for cars in recent months and increased consumption in the US will lead to an increase in demand for gasoline and distillates in the world by 0.993 million barrels per day. This will have a positive impact on oil and oil products stocks, which OPEC and non-OPEC countries seek to reduce by limiting production. The main driver of the reduction in petroleum products OPEC sees consumption in the US. For the first time in past 25 years, the demand for diesel fuel and gasoline in the US increased by 846 thousand barrels per day. The reserves of gasoline and distillates in the US declined over in 2017 and fell below the average for five years. Oil reserves also fell below this indicator. Nowadays, OPEC continues to play a huge role in the functioning of the world economy, but it is clear that its role in the international arena is getting lower and lower every year. This is due to many indicators. Here are the main ones. First, due to the fact that already today OPEC is not able to cope with the fall in oil prices, it has to seek support from other oil-exporting countries, that is, its dependence on other countries increases. Secondly, the recent rationalization of the use of natural resources and the shift to the use of alternative energy sources, leads to a reduction in demand for oil. In these conditions, OPEC pursues a policy of reducing the production of oil. But, with the reduction in oil production in the OPEC countries, the states that are not included in it, on the contrary, are trying to increase production of «black gold», gradually reducing the role of OPEC in the functioning of the world economy. The dynamics of energy demand is affected by many factors, including weather, the price of petroleum products, the growth rate of the economy, etc. The proposal is also difficult to calculate. Despite the very specific goals of the OPEC + countries and other exporters, there are periodic accidents, spills, man-made and natural disasters that can dramatically change the market situation. Many risks have to be neglected. IEA, OPEC and the US Ministry of Energy regularly publish their estimates of the future oil market and are the most authoritative organizations in this regard. This article considers the dynamic of changes in the world market of «black gold», also many factors due to the influence of various geopolitical processes on extraction and export of oil. Key words: oil, price, OPEC, petroleum, barrel

Supramolecular strategy to construct quantum dot-based sensors for detection of paraoxon

© 2018 Elsevier B.V. The development of advanced tools for sensing specific materials remains an ongoing challenge. Detailed below is a new quantum dot (QD)-based sensor via supramolecular interactions, demonstrating a novel simplicity of design to obtain sensitive QDs while avoiding their covalent cross-linking. A simple label-free and turn-off method for the detection of paraoxon and its degradation products in aqueous media was proposed by using the fluorescent QD/surfactant/cyclodextrin supramolecular system. This nanocomposite was prepared from 3-mercaptopropionic acid-capped CdTe QDs coated with cetyltrimethylammonium bromide (CTAB) through electrostatic self-assembly. Further nanocomposite modification by β-cyclodextrin (β-CD), thanks to hydrophobic interaction between cetyl tails of surfactants and inner cavity of macrocycle contributed to an increase in emission intensity and stability in aqueous solution. The strong fluorescence of CdTe/CTAB/β-CD nanocomposite can be effectively quenched by the addition of paraoxon due to the host–guest complexation between β-CD cavity and paraoxon degradation product. The functionality of the paraoxon sensor was also tested with blood samples of paraoxon-poisoned rats (1/2 × LD50). These fluorescent nanocomposites were obtained by using the simple supramolecular method to coat QDs with surfactant–cyclodextrin shells. This coating strategy potentially offers common method for the functionalization of QDs and avoids time-consuming synthesis procedures